Oh my goodness! did you call the police? I was in the line of hunter fire when riding my road bike in college. I was riding on a road and the hunters were shooting at doves that were on the electric wires above me. I rode straight to the police and they said that hunters could not shoot at roads. Whatever. They did!
There's no way I would mountain bike during hunting season around here. Hunters are everywhere outside the state parks. Find out when various season are and don't go out on the trails. It's not worth the risk. If you must, wear hunters orange, NOT hi-viz yellow. Hunters are looking for orange, and yellow does not compute in their minds. I've read that hi-viz yellow is appropriate for urban settings, but that orange is better in rural and woods settings. Definitely during hunting season, orange us the way to go.
Jeeze, that really shocking that they came so close! Be careful!